Abstract: In order to research the response of the seamount bacteria to exogenous organic matters, and better understand the diversity of seamount bacteria and their roles in carbon cycles in the deep sea, a ten-month deep-sea in situ enrichment was developed at the top (2 929 m) and bottom (4 707 m) of the seamount of Philippine Sea in western Pacific Ocean. Different substrates including alkane-sulfur mixture (CS), activated sludge (HX), chitin (JDZ), D-Aspartic acid (D-Asp), Dimethyl sulfone (DMSO2) and poly-β-hydroxybutyric acid (PHB) were added into a circulation chamber of deep-sea water incubation system. The bacterial communities of enriched samples were analyzed with high-throughput sequencing technology and the cultivatable bacteria were isolated and identified with the spread plate method. Results of high-throughput sequencing of 16S rRNA genes showed that bacterial communities, including 200 species of 150 genera in 96 families and 61 orders in 27 classes of 15 phyla，were enriched in 6 samples. The bacterial composition of enriched samples with different substrates differed from each other significantly, indicating that different substrates selectively led to specific enriched bacterial communities. Results showed that Roseobacter_Clade_NAC11-7_Lineage and Moritella were dominated in alkane-sulfur mixture enrichments, Pseudoalteromonas and Fusibacter in activated sludge enrichments, Vibrio in chitin enrichments, Pseudoalteromonas in D-Asp enrichments, Pseudoalteromonas and Ruegeria in DMSO2 enrichments, Ruegeria and Fusibacter in PHB enrichments. Besides, a total of 277 bacterial strains were isolated and from these six different deep-sea in situ enriched samples and were identified to be 92 species of 63 genera in 35 families and 19 orders in 8 classes of 5 phyla. Among them 62 potential novel species and 5 potential novel families were obtained, indicating the diversity and novelty of marine microorganisms in the seamount of Philippine Sea. The potential ecological roles and metabolic mechanisms in element cycles of these cultural bacteria in deep sea needs to be further explored.